Search

Herein, a magnetic MXenes based composite (Fe

A bio-adsorbent (DAWP-PEI-β-CD) was facilely prepared by introducing polyethylenimine (PEI) and β-cyclodextrin (β-CD) into dialdehyde waste paper (DAWP) via a facile two-step method. Various physicochemical and spectroscopic techniques (FT-IR, XRD, SEM, NMR, XPS) were applied to characterize the structure, morphology and composition of the as-prepared adsorbents. Investigation results showed that the pH values, reaction temperature and contact time played a vital role in uptake of Eu(III) and Au(III). Meanwhile, the adsorption behavior of Eu(III) and Au(III) could be fitted felicitously with the Langmuir and the Pseudo-second-order models, and the saturated adsorption amounts of Eu(III) (pH = 6.0) and Au(III) (pH = 2.0) onto DAWP-PEI-β-CD were 424.2 and 241.3 mg/g, respectively. Further advanced spectroscopy analysis revealed that the elimination of Eu(III) was attributed to host-guest inclusion and surface complexation interaction, while adsorption of Au(III) might stem from a combination of electrostatic attraction, chelation, host-guest inclusion and redox interaction. This study demonstrated that DAWP-PEI-β-CD was a promising environmental functional material to separation and enrichment of Eu(III) and Au(III) from contaminated water.

Herein, a potential bio-adsorbent (DACS-CA) was formed via immobilizing caffeic acid (CA) on dialdehyde corn starch (DACS) for Cr(VI) removal. The characterization techniques such as IR, Raman, XPS and 13C NMR were performed to analyze surface elements and functional groups on the as-prepared sorbents. Batch experiments revealed that the maximum Cr(VI) removal amount (96.45 mg/g) took place at a pH value of 3.0, adsorption temperatures of 333 K and solid-liquid ratio of 0.2. The isotherms studies found that the Cr(VI) removal of DACS-CA was monolayer adsorption, while the kinetics analysis revealed that chemisorption was the main power for removal process. Characterization analysis found that about Cr(VI) (53.02%) and Cr(III) (46.98%) species co-existed onto the surface of DACS-CA, which implied that a redox reaction may be occurred between Cr(VI) and the bio-adsorbent. Namely, Cr(VI) was first loaded on DACS-CA via electrostatic interaction, subsequently Cr(VI) was partially transformed into Cr(III) by reductive functional groups, meanwhile the resulting Cr(III) was immobilized by the carboxyl groups of DACS-CA. Thus, this bio-adsorbent could serve as an efficient sorbent for the removal of Cr(VI) from wastewater in environmental pollution cleanup.

A highly efficient fiber-based adsorbent (DAVFs-CS) was developed via decoration of chitosan (CS) on the dialdehyde viscose fibers (DAVFs) substrate, and employed to selective separation of precious metals from simulated contaminated water. The surface functionalization of the solid material was probed using the Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TGA) and nuclear magnetic resonance (NMR) technique. The batch characteristic results showed that the maximum uptake capacities of DAVFs-CS were higher up to 322 mg/g and 207 mg/g for Au(III) and Pd(II) at optimal pH 2.0 and 3.0, which exhibited competitiveness with the majority of the reported adsorbents. Meanwhile, the adsorption data were in accordance with Langmuir and PSO equations, which indicated that the monolayer chemisorption dominated the adsorption process. The competitive adsorption study showed that the removal efficiency of Au(III) was not susceptible to the co-existing impurities. Adsorption mechanism study revealed that the negative Au(III) or Pd(II) species were firstly adsorbed on DAVFs-CS via the protonated amino groups, subsequently the partially reduction of them to zero-valent gold and palladium with the help of reductive functional groups. Thus, DAVFs-CS could be as a promising adsorbent to recovery of precious metals owning to its unique adsorption mechanism and excellent adsorption performance.

Herein, a magnetic amine-functionalized mesoporous silica SBA-15 (Fe3O4@SBA-15-PDA/HBP-NH2) adsorbent was fabricated by loading Fe3O4 nano-particles on amino-terminated hyperbranched polymers (HBP-NH2) functionalized SBA-15 and exploited for chromium (VI) and uranium (VI) elimination. The morphologies and microstructures of as-obtained materials were observed using different physicochemical and spectroscopic techniques. Meanwhile, batch experiments were performed to investigate the impacts of various water environment conditions on removal process including solution pH, equilibrium time and temperatures. The maximum adsorption capacities of U(VI) and Cr(VI) on Fe3O4@SBA-15-PDA/HBP-NH2 reached up to 77.4 mg/g and 66.5 mg/g under optimal water environment conditions. Moreover, the characterization analysis manifested that removal of U(VI) was fulfilled through the surface complexation with amino and phenolic hydroxyl groups, while Cr(VI) were firstly electrostatically adsorbed, and subsequently reduced to less toxic Cr(III) by phenolic hydroxyl groups. These findings demonstrated that this new magnetic amine-functionalized SBA-15 could be considered as valuable materials in environmental cleanup.

Herein, a composite material (nZVI@SBA-15-PDA/PEI) was developed by loading nanoscale zero-valent iron (nZVI) on polydopamine-decorated SBA-15 for Cr(VI) and U(VI) removal. The structure, morphology and composition of the as-prepared composites were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffractometer (XRD) and fourier transform infrared spectroscopy (FT-IR) techniques. The experimental results demonstrated that the water environmental conditions played an important role in elimination of Cr(VI) and U(VI), such as pH values, pollutant concentrations and equilibrium time. Meanwhile, the fitted data displayed that the elimination process could be more accurately explained by the Langmuir and pseudo-second-order kinetic models, and the maximum removal capacities for Cr(VI) and U(VI) were 44.05 mg/g (pH = 3.0) and 57.78 mg/g (pH = 6.0) at 298 K, respectively. The characterization analysis conformed that the elimination mechanisms were proposed as a two-step interaction. Namely, both Cr(VI) and U(VI) were firstly attached onto the surface of composite materials via electrostatic interaction or surface complex reaction, and subsequently about 47.1% of U(VI) and 55.7% Cr(VI) were reduced to U(IV) and Cr(III) by nZVI. Thus, this nZVI composites exhibited a high potential to eliminate Cr(VI) and U(VI) from polluted water environment.

Background Increasing researches have reported that circular RNA UBAP2 (circUBAP2) may be a potential prognosis biomarker and participate in the development of several cancers; however, the role of circUBAP2 in cervical cancer (CC) remains largely unclear. Methods We applied qRT-PCR and Western blot to examine expression levels of circUBAP2, miR-361-3p, SOX4, Bax, Bcl-2, Cleaved caspase 3, N-cadherin, Vimentin and E-cadherin. Cell proliferation, apoptosis, invasion and migration were analyzed by MTT assay, Flow cytometry, and Transwell assay, respectively. The interaction between miR-361-3p and circUBAP2 or SOX4 was confirmed by luciferase reporter assay and pull-down assay. Murine xenograft model was established by injecting SiHa cells which stably transfected sh-circUBAP2. Results CircUBAP2 was up-regulated in CC tissues and cell lines and high circUBAP2 expression predicated poor outcome. Knockdown of circUBAP2 suppressed cell proliferation, migration, invasion and EMT, while induced apoptosis in CC in vitro, and inhibited tumor growth and metastasis in vivo. MiR-361-3p directly bound to circUBAP2 or SOX4, and circUBAP2 could regulate SOX4 expression by sponging miR-361-3p in CC cells. Furthermore, rescue assay results demonstrated that the inhibitory effects of circUBAP2 knockdown on cell growth and metastasis were partially reversed by miR-361-3p down-regulation or SOX4 up-regulation in CC. Conclusion CircUBAP2 represents a prognostic marker and contributes to tumor growth and metastasis via modulating miR-361-3p/SOX4 axis in CC, which indicates a potential therapeutic target for CC treatment.

A novel fibrous adsorbent (DAVSF-CA) was synthesized via grafting caffeic acid (CA) onto dialdehyde viscose staple fiber (DAVSF), and used to selectively adsorb Au(III) from simulated wastewater. Fourier Transform Infrared (FTIR), X-ray Photoelectron (XPS) and Nuclear Magnetic Resonance (NMR) spectra confirmed that caffeic acid was successfully grafted on DAVSF through condensation reaction. Adsorption experiments revealed that the adsorption of Au(III) on DAVSF-CA was extremely dependent on pH values and temperatures, and the maximum adsorption capacity of 3.71 mmol/g for Au(III) was obtained at pH 3.0 and 333 K according to the Langmuir fitting. High temperature was favorable for Au(III) adsorption because the adsorption of Au(III) on the DAVSF-CA was endothermic. The competitive adsorption demonstrated that DAVSF-CA had a good preference to Au(III) adsorption in the presence of some coexisting pollutants. The adsorption isotherm data of Au(III) were well-described by the Langmuir model, while the kinetic data were fitted well by the Pseudo-second-order equation. The major reaction involving the reduction of Au(III) to Au(0) was identified by XPS and XRD analysis. Namely, Au(III) was first captured on protonated functional groups via electrostatic adsorption, and then reduced to its elemental form and formed the nano-particles on the adsorbent surfaces.

Effective recovery of high-value heavy metals from electroplating wastewater is of great significance, but recovering nickel ions from real electroplating wastewater as nickel sheet has not been reported. In this study, the pilot-scale fixed-bed resin adsorption was conducted to recover Ni(II) ions from real nickel plating wastewater, and then the concentrated Ni(II) ions in the regenerated solution were reduced to nickel sheet via electrodeposition. A commercial cation-exchange resin was selected and the optimal resin adsorption and regeneration conditions were investigated. The resin exhibited an adsorption capacity of 63 mg/g for Ni(II) ions, and the average amount of treated water was 84.6 bed volumes (BV) in the pilot-scale experiments. After the adsorption by two ion-exchange resin columns in series and one chelating resin column, the concentrations of Ni(II) in the treated wastewater were below 0.1 mg/L. After the regeneration of the spent resin using 3 BVof 4% (w/w) HCl solution, 1.5 BV of concentrated neutral nickel solution (>30 g/L) was obtained and used in the subsequent electrodeposition process. Using the aeration method, alkali and water required in resin activation process were greatly reduced to 2 BV and 3 BV, respectively. Under the optimal electrodeposition conditions, 95.6% of Ni(II) in desorption eluent could be recovered as the elemental nickel on the cathode. The total treatment cost for the resin adsorption and regeneration as well as the electrodeposition was calculated.

A hyper-cross-linked resin (PDVBpc) based solid amine adsorbent was synthesized by suspension polymerization of divinylbenzene (DVB) and a Friedel–Crafts alkylation reaction, followed by impregnation with tetraethylenepentamine (TEPA), for CO2 capture. The results showed that the specific surface area and pore volume of the initial porous polymer (PDVB) remarkably increased after the Friedel–Crafts alkylation reaction, which was beneficial for increasing the loading of TEPA and the adsorption of CO2. To determine the CO2 adsorption performance, certain factors, including the TEPA loading, flow rate, CO2 concentration and adsorption temperature, were investigated. The maximum adsorbed amount of CO2 (3.11 mmol g−1) was achieved at 25 °C and a CO2 concentration of 10 vol% when the flow rate was 30 mL min−1 and the TEPA loading was 30 wt%. The optimal TEPA loading could provide sufficient active sites for CO2 capture, whereas excessive loading may lead to aggregation of the adsorbent and blockage of pore channels. An increase in temperature was unfavourable for the adsorption of CO2, because the reaction between amine groups and carbon dioxide was exothermic. A high CO2 concentration would reduce the breakthrough time but would not affect the adsorption capacity for CO2. The experimental data fitted the Avrami model well at different temperatures, which indicated that both physisorption and chemisorption contributed to the adsorption of CO2. Thus, a promising material for the adsorption of CO2 was obtained via the functionalization with TEPA of a hyper-crosslinked resin.

A series of porous polymers was synthesized by a suspension polymerization of divinylbenzene (DVB) and ethylene glycol dimethyl acrylate (EGDMA), which was further functionalized with polyethyleneimine (PEI) for CO 2 capture. The results showed that the synthesized DVB and EGDMA (DE) copolymers were an effective support for loading PEI because of its larger pore size and specific surfaces area. It was found that DE (30, 10) loaded with 30 wt% PEI exhibited a higher CO 2 adsorption amount of 3.28 mmol/g at 25 °C under dry condition. The CO 2 adsorption capacity would decline gradually as the temperature continuously raised, for the reaction between CO 2 and amine groups was an exothermic reaction. The kinetics study showed that Avrami kinetic model could accurately describe the whole CO 2 adsorption process, suggesting that both physical adsorption and chemical adsorption were involved with the CO 2 adsorption process. The intraparticle diffusion and Boyd’s film diffusion models were applied to investigate the CO 2 diffusion mechanism, the intraparticle diffusion model could well distinguish the rate-limiting step during CO 2 adsorption process. This solid amine adsorbent could be regenerated with nitrogen stream at 75 °C, and it kept stable CO 2 adsorption capacity after eight adsorption-desorption cycles. All these features indicated that this porous polymer based adsorbent has a high potential for CO 2 capture and separation from flue gas.

The commercial porous phenolic resins (XAD-761) were selected as the support material for loading PEI to prepare solid amine adsorbents. The CO2 adsorption performances of the solid amine adsorbent was evaluated. The experimental results showed that when the PEI loading amount was 40 wt% on XAD-761, the CO2 adsorption amount could reach up to 3.85 mmol/g at 25 °C under dry condition. Meanwhile, the CO2 adsorption capacity declined as the temperature continuously raised, for the reaction between CO2 and amine groups was an exothermic reaction. The existence of water improved the utilization efficiency of amine groups on the adsorbents and finally lead to a great promoting of the CO2 adsorption amount. The kinetics study showed that Avrami kinetic model fitted better than the pseudo-first order and the pseudo-second order kinetic models for CO2 adsorption, suggesting that both physisorption and chemisorption were involved in the CO2 adsorption process of the prepared adsorbent. Moreover, the adsorbent exhibited good stability after five adsorption–desorption cycles. All these results indicated that this solid amine adsorbent has a high potential for CO2 capture and separation from flue gas.

Our previous results have shown that direct fluorination can modulate surface electrical properties and suppress surface charge accumulation of epoxy insulators, and thus has potential applications for improving the flashover performance of epoxy spacers in gas-insulated equipment. In this study, to investigate the resistance of the fluorinated epoxy surface layer to partial discharge in SF 6 gas, surface fluorinated epoxy samples together unfluorinated (virgin) ones were corona treated using a multi-needle-to-plate electrode system. ATR-IR analyses and SEM surface and cross section images show that the corona discharge caused the chemical modification and chain scission at some weak points in the fluorinated layer and the crosslinking reaction, and thus led to the formation of nodules on the corona treated fluorinated surface. However, the corona treatment did not change the fluorinated layer thickness. In contrast with this, severe degradation, most likely in the form of etching, occurred for the virgin surface layer during the same treatment. Measurements of surface potential decay and water contact angle indicate that the corona discharge obviously reduced surface conduction of the fluorinated sample, and rendered the surface conduction insensitive to humidity although the corona treatment almost did not change surface wettability of the fluorinated sample. On the contrary, the measurements show that surface conduction of the virgin sample increased and became sensitive to humidity after the corona treatment.

A novel bio-adsorbent (DAVF-PT) was prepared by the introduction of persimmon tannin (PT) on the surface of viscose fiber (VF) through condensation reaction. The adsorbent was applied to the adsorption of Au(III) and Pd(II) from aqueous solution. Batch adsorption experiment found that the adsorption performance of DAVF-PT for Au(III) and Pd(II) was closely related to pH of solution, initial metal ion concentration as well as co-existing metal ions. The adsorption isotherms data of Au(III) and Pd(II) on DAVF-PT could be best explained by the Langmuir equation, and the fitted maximum adsorption amounts for Au(III) and Pd(II) were 535 mg/g and 214 mg/g, much higher than those similar adsorbents reported in the literatures. The thermodynamic study revealed that adsorption reaction was an endothermic, spontaneous and entropy increase process. Furthermore, the kinetics data of Au(III) and Pd(II) adsorption on DAVF-PT obeyed the Pseudo-second-order equation, indicating that the chemical adsorption was the mainly rate-limiting step. The EDS, XPS and XPD analysis confirmed that the gold and palladium ions were reduced to metallic state following adsorption, while the phenolic group was simultaneously converted into quinone group, indicating the potential use of this novel fiber-based adsorbent in the recovery of precious metal ions from wastewater.

A three-dimensional finite element model of 2024 aluminum hi-bolted joint was established. Hi-bolts installation and pre-tightening force applied were simulated, then distal alternating load on middle plate of the joint. Fatigue life was predicted with FE-SAFE soft, and verified by experiment. The simulation results show that middle plate is the weakest plate in the plates of the joint. Hoop residual compressive stress increases with raising interference, and decreases gradually from the hole to the outer edge. Fatigue life is longer with interference fit than clearance, and it is benefit for fatigue life improvement with interference from 0.08 to 0.14 mm. While fatigue test results show that failure origins from No. 2 hole of the middle plate. The fatigue life grow longer with interference from 0 to 0.11 mm, then shorten with 0.14 mm interference. The fatigue life is longest with 0.11 mm interference. The suggested interference for engineering is 0.08–0.11 mm for possible defects with 0.14 mm interference.

Split-sleeve cold expansion processing was employed on the 2024-T3 aluminum alloy plate. Fatigue lives were compared according different expansion, and then the relationship of fatigue life and expansion was analyzed. Residual stresses were measured with different expansion, and the fatigue fractograph was analyzed by SEM. The results show that the split-sleeve cold expansion can obtain longer life compared with the non strengthened hole. The maximum fatigue life increased to 12 times with 6% expansion. When over 6% expansion, fatigue life began to decrease. The split-sleeve cold expansion can form beneficial residual compressive stress, and deferred the fatigue crack initiation. The fatigue fractograph shows quasi-cleavage fracture.

An efficient fibrous adsorbent (PANF-TETA-PT) was prepared via grafting triethylenetetramine (TETA) on polyacrylonitrile fiber (PANF), followed by persimmon tannin (PT) immobilizing. Detailed characterization certified that plenty amounts of amino and phenolic hydroxyl groups existed on the surface of PANF-TETA-PT, which would provide excellent active sites for Au(III) adsorption. The batch characteristic results found that the adsorption equilibrium data could be fitted well with Langmuir equation, while the obtained kinetic data were consistent with the Pseudo-second-order equation. The maximum equilibrium adsorption capacity of PANF-TETA-PT towards Au(III) (801.2 mg/g) was apparently superior than that of the reported adsorbents, and the competitive adsorption showed that PANF-TETA-PT had a good preference to adsorption Au(III) in spite of some coexisting pollutants. The characterization analysis of Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer spectrum (XRD) revealed that the electrostatic attraction and chelation dominated the uptake of Au(III) on PANF-TETA-PT, in which a part of loaded Au(III) was reduced to Au particles with the help of reductive functional groups. Thus, this adsorbent could be as a promising candidate to separation and preconcentration of Au(III) from wastewater.

Aminated adsorbents are efficient in capturing high concentrations of CO2, while their efficiency in air purifier for the removal of low concentrations of CO2 from indoor air remains unclear. In this study, a polyethyleneimine-impregnated resin (PEI-MR10) was prepared and used to remove indoor CO2, and its regeneration at low temperatures was evaluated. PEI loading narrowed the pore size distribution but increased the average pore size of the PEI-MR10. The PEI-MR10 with small particle size (0.250–0.425 mm) exhibited higher adsorption capacity and faster adsorption rate than the bigger one. The PEI-MR10 was able to remove all CO2 during the first 2 h with an initial CO2 concentration of 1000 ppm. Under variable indoor conditions, the adsorbed amounts of CO2 could maintain high values from 90 to 136 mg/g. At a relative humidity of 50%, the adsorbed amount on the PEI-MR10 for 1000 ppm CO2 reached 128.4 mg/g. In consideration of real application in air purifier, a cost-effective regeneration method using ambient air was adopted, and the spent PEI-MR10 was regenerated at low temperatures no more than 70 °C. The desorption efficiency of CO2 increased with increasing temperatures, and the best regeneration was obtained at 70 °C. The adsorbed amount of CO2 on the first-regenerated PEI-MR10 decreased significantly, but the adsorbent maintained stable adsorption capacity of about 80 mg/g after three adsorption-regeneration cycles. This study demonstrated that PEI-MR10 was an effective adsorbent for CO2 removal from indoor air.

Our recent studies have indicated that direct fluorination can modulate surface electrical properties and suppress surface charge accumulation of epoxy resin insulators. Further, to investigate the resistance to corona discharge of the fluorinated surface layer, the surface fluorinated epoxy sample together the unfluorinated (virgin) one were corona treated in synthetic air using a multi-needle-to-plate electrode system. ATR-IR and EDS analyses and SEM surface and cross section images show that the corona treatment did not lead to cleavage of the C-F bond in the fluorinated layer and to changes in its surface morphology and thickness, although the treatment attacked the cross-linked products generated by fluorination and the weak points at which the fluorine substitution or addition reaction took place only partially. In contrast with this, the virgin surface layer was degraded by the corona treatment, likely in the form of ablation. Measurements of surface potential decay and water contact angle indicate that the corona treatment caused a decrease in surface electrical conduction of the fluorinated sample due to the attack on the cross-linked products and the weak points, but did not change its surface wettability and did not produce soluble degradation products in the fluorinated layer. On the contrary, the measurements show that the corona treatment led to an increase in surface conduction of the virgin sample, and surface conduction of the corona treated virgin sample was highly sensitive to the humidity due to the presence of soluble degradation products on the surface.

In order to investigate the CO2 corrosion behavior and the grooving corrosion susceptibility of electric resistance welded tubes of the Q125 grade, the high temperature and high pressure autoclave was employed to conduct CO2 corrosion experiments for the welded joint. The mechanisms of grooving corrosion and the factors influencing grooving corrosion susceptibility were identified by electrochemical measurement, microstructure observation, residual stress examination, micro-region composition and orientation analysis. The CO2 corrosion results show that the corrosion resistance of the base material is the best, followed by heat-affected zone and the welded seam is the worst. The grooving corrosion occurred in the welded seam, and the grooving corrosion susceptibility of welded seam is relativity high. The dominated reason for the grooving corrosion of the electric resistance welded joint is the notable inclusions consisting of MnS as the main content in the welded seam. The proportion of high-angle grain boundaries in the welding zone is higher than that of base metal and the heat affected zone, which plays an important role in the corrosion behavior of the welded seam.

Electroplating sludge as the hazardous waste produced from the electroplating wastewater treatment plants, is also precious resources of various transition metals. In this study, the novel calcined electroplating sludge (CES) was prepared via facile calcination and subsequently used as an effective bifunctional material for removing Ni(II)-citrate in electroplating wastewater. The CES displayed a high removal efficiency of Ni(II)-citrate in the CES/H2O2 system via oxidative degradation of complex compounds and adsorptive removal of Ni2+. The high removal efficiency could be ascribed to the excellent catalysis and adsorption ability of the CES. The Fe and Cu oxides in the CES were considered as reactive components for the activation of H2O2 to degrade the complex compound, while the oxygen-containing functional groups on the CES surfaces were responsible for the adsorption of Ni2+. Various parameters affecting Ni(II)-citrate in the electroplating wastewater removal efficiency were tested. With the addition of 50 mmol/L H2O2 and 1.5 g/L CES, 87% of the total nickel could be removed within 50 min when the total nickel concentration in the Ni(II)-citrate containing electroplating wastewater was 283 mg/L. This study provides a new method for the treatment of electroplating wastewater containing nickel-organic complexes by the electroplating sludge wastes. This technology can reduce the treatment cost of electroplating wastewater and achieve the concept of disposal waste with waste.

Both the raw electroplating sludge (RES) waste and the calcined electroplating sludge (CES) were utilized to adsorb nickel from the real electroplating wastewater. The CES was obtained via calcination treatment at 500 °C, and the CES and RES were characterized by X-ray fluorescence (XRF), Fourier transform infrared spectrometer (FT-IR), X-ray powder diffraction (XRD). Adsorption isotherm results showed that the maximum adsorption capacities of Ni2+ on the CES and RES were 163.6 and 210.9 mg/g according to the Langmuir fitting, respectively. In the real nickel-containing wastewater treatment, the RES exhibited much higher adsorption capacity for Ni2+ than commonly used adsorbents including coal-based activated carbon (CAC), strong acid cation-exchange resin (D001), weak acid cation-exchange resin (D113) and amino carboxylic acid chelating resin (D463). The adsorption mechanisms of Ni2+ on the RES and CES mainly included ion exchange and surface complexation. The large amount of Ca2+ in the adsorbents played an important role in the adsorption of Ni2+ via cation exchange, and the hydroxyl and carboxyl groups on the adsorbent were also responsible for Ni2+ adsorption. Therefore, the electroplating sludge waste is an efficient adsorbent for Ni2+ removal from high concentrations of nickel-containing electroplating wastewater. This study provides a new method for the utilization of electroplating sludge as efficient adsorbents before being treated as hazardous waste, showing the feasible concept of disposal waste with waste.

Resin adsorption is considered as a promising method to recover gold ions from wastewater, but further reduction reaction is required to convert gold ions into particles. In this study, a crosslinked polyethyleneimine resin (CPEIR) was developed via a suspension polymerization of polyethyleneimine (PEI) and ethylene glycol diglycidyl ether (EGDE) for gold recovery. The Au(III) adsorption capacities of CPEIR were significantly impacted by solution pH and initial Au(III) concentrations but unaffected by co-existing metal ions. Compared with commercial anion-exchange resin IRA400, the CPEIR exhibited higher sorption amount and selectivity for Au(III) due to its high density of amine and hydroxyl groups on the surfaces. The adsorption isotherm of Au(III) on CPEIR was well described by the Langmuir equation, and the maximum uptake amount of Au(III) was high up to 943.5 mg/g, much higher than the reported sorbents. The adsorption kinetic data on the CPEIR were fitted well by the Pseudo-second-order equation, and the intraparticle diffusion was found to be the rate-controlling process of Au(III) adsorption. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis confirmed that Au(III) ions were adsorbed on the CPEIR via electrostatic attraction and chelating interaction, and subsequently the partial loaded Au(III) ions were reduced to elemental gold whereas the hydroxyl groups of CPEIR were oxidized to carbonyl groups.

The heat treatments of 0Cr18Ni9Ti (0Cr) and 1Cr18Ni9Ti (1Cr) stainless steel tubes, which are commonly used to produce the rivet parts, were performed under different experimental conditions. The mechanical properties of the two stainless steel tubes after solution processes were also tested to study the influences of experimental temperature, holding time and cooling rate. In addition, the microstructures of these two stainless steel tubes were observed by using optical microscope (OM) and scanning electronic microscope (SEM). The results showed that these two stainless steel tubes possessed similar microstructures after solution process, which composed of austenite grains. However, compared with 1Cr stainless steel tubes used in the manufacturing of rivet sleeve, 0Cr stainless steel tubes exhibited more significant holding time and solution temperature dependence of microstructures and mechanical properties. These performance variation sections are in favor in adjusting the structural parameters and installation process of rivets.

In the present work, a novel adsorbent to effectively adsorb Ag+ from an aqueous solution has been prepared by immobilizing persimmon tannin (PT) on collagen fiber. The adsorption capacity of Ag+ on the immobilized PT were evaluated under various treatment conditions, including the initial solution pH, solid–liquid ratio, temperature, and initial concentration of Ag+. The results showed that the effect of initial solution pH, solid–liquid ratio, and initial concentration of Ag+ on the adsorption capacity were remarkable, while the influence of temperature was insignificant. The adsorption capacity reached 1947 mg/g at 303 K and pH 7.0 when the initial concentration of Ag+ was 800 mg/L and solid–liquid ratio was 0.4. Adsorption equilibrium isotherms of Ag+ on the surface of the adsorbent fibers were studied using Freundlich and Langmuir isotherms. The experimental data fitted best to the Freundlich models. Also, the immobilized PT before and after adsorption of Ag+ was characterized by Fourier tran...

Surface fluorinated epoxy samples together with the unfluorinated (virgin) ones were exposed to the SF 6 corona discharge generated by a multi-needle-to-plate electrode system, to investigate the resistance of the fluorinated layer to the corona discharge. SEM observations and ATR-IR analyses show that thickness of the fluorinated layer was not reduced and no clear evidence for the cleavage of C-F bonds by the corona discharge, although it caused surface morphology change due to attack on some weak points in the fluorinated layer, chain scission, and cross-linking reaction. In contrast with this, the virgin surface layer was degraded by the corona exposure in the form of ablation. Measurements of surface potential and water contact angle indicate that the corona discharge reduced surface conduction of the fluorinated sample and rendered the surface conduction insensitive to humidity. On the contrary, the corona exposure led to an increase in surface conduction of the virgin sample, which is sensitive to humidity.

Within the Sino-Italian environmental protection cooperation framework established in 2002, a comprehensive air quality monitoring network has been developed in urban Suzhou, a medium-sized Chinese city, in compliance with European standards (Directive 96/62/EC). This paper is among the first attempts to present a systematic and scientific analysis of benzene, toluene, and xylenes (BTX) pollution in China. It presents our analysis of BTX space-related and time-related measurement results. Background BTX concentrations were investigated by passive sampler Analyst(R) in 2003. We depicted the spatial distribution of average BTX concentrations collected from three 15-day campaigns on isoconcentration maps. This is the first time such detailed BTX concentration maps have been developed in China in a city scale. Continuous measurement of BTX by automatic gas chromatography was carried out at two fixed monitoring stations, one in an urban residential zone and one in a heavy traffic zone, from April to December 2005. The results show similar seasonal trends at both sites, the similarities reaching their greatest level in December and their lowest level in August. The average daily profile of BTX shows greater fluctuation in spring and winter with clear morning and evening peaks. Daily average benzene, toluene, and m,p-xylenes concentrations for the study period were 2.64, 11.52, and 3.52 microg m(-3), respectively. The benzene/toluene ratio we found was lower in Suzhou than those published in studies of other worldwide cities, which indicates serious levels of toluene pollution from local stationary sources. The similarities in seasonal trend and spatial distribution in these manual and automatic measurement results were compared with each other, though the concentration values differed.

Vertical distribution of traffic-related pollutants inside an open street-canyon were observed in Suzhou, P.R. China, in 2005. The aim was to explore transfer and diffusion characteristics of vehicular exhaust emissions, as well as monitoring constraints associated with street canyons, courtyards and enclosed spaces. Vertical wind speed was found to strongly affect the fluctuation of all the pollutants. Daily average concentrations of NO x , NO 2 and NO, as well as NO 2 /NO x ratio, were found to vary significantly alongside the vertical, proportionate to different average daily trends. Oxidation processes and photochemical activity are discussed to explain these phenomena. Daily CO trends were found to track closely with both NO x and Benzene, while the corresponding ratios were different relative to other published works. Different emission factors and driving conditions, as well as other emission sources types (especially for Benzene) are used to explain this point.